The general objective of these studies is to investigate the physical properties of the pigment melanin and other biological molecules and to relate these properties to the preferential destruction of pigmented tissues by ultrasound and other environmental agents. This knowledge is then to be used to develop controlled methods for the preferential killing of melanotic tumor cells. A further objective is to investigate the mechanistic aspects of the effects of ultrasound on both pigmented and nonpigmented cells and determine the relationship of these effects to the electronic properties of the various biological molecules, including melanin. The goals for the current year were to further investigate the electronic properties of biomolecules and to gain insight into the role that water plays in the interaction of molecules which are known to dope melanin. Water is known to be essential to the amorphous semiconductor properties of the biological amorphous semiconductors. Investigations into the interaction of these doping molecules with ultrasound related to the killing of pigmented cells was to be extended.